Newbee unable to machine a flat top

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jdonaldson
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Joined: Mon Sep 06, 2010 11:05 am

Re: Newbee unable to machine a flat top

Post by jdonaldson »

Thanks for all the input, but I feel like a dog chasing my tail. Can someone tell me what the acceptiable degree of acuracy ( total runout) I should be able to obtain with the Shark at 3" , 6" radius. I think maybe I'm thinking this machine can be more precise that what it can be.

Thanks again for your input

John
shark pro, Aspire 4 , VCP 6.5 , cut 3d ,

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Consultingwoodworker
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Joined: Fri Jul 02, 2010 7:37 am
Location: Nashville area
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Re: Newbee unable to machine a flat top

Post by Consultingwoodworker »

When I surface my table, there is no visible line left behind.

I have found this system to be very much more accurate than I had thought it would be.

Look at the clamping plate that holds the router. Make sure it is square and that the router is not being held crooked. Also check it front to back and be sure it is not canted.

Something is no kosher with the set up of your Z head, that's where to look for the solution.

Ralph

jdonaldson
Posts: 39
Joined: Mon Sep 06, 2010 11:05 am

Re: Newbee unable to machine a flat top

Post by jdonaldson »

Ralph,

Can you tell me what your actual runout is, I tried shimming the router this weekend and since its better but still not touching all the way around probably .09 off still that maybe my problems in the gantry. There really out to be some specific directions for squaring this machine up.

John
shark pro, Aspire 4 , VCP 6.5 , cut 3d ,

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RhB_HJ
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Re: Newbee unable to machine a flat top

Post by RhB_HJ »

John,

On how to test/adjust the machine (pretty well any one of this type!)
First you need the Y-axis as parallel as possible to the table. Move the gantry end to end, should be a straight line with a slight dip going through the centre. Shim either end if necessary.
Same routine for the X-axis. To straighten you need to loosen the mounting bolts of the gantry uprights.
Z-axis and router axis, swing out 360º with test indicator on an extension to get a 12" diameter swing. To be sure that the channels in the table surface don't interfere use a setting/test block between table and indicator arm. If it is off by much in the Y-direction run the Z-axis up and down with the indicator along a master square. Measure same for X-axis. Compare those measurements to the results from swinging out the router axis.
To get the spindle square adjust the gantry: tilt the uprights in the Y-axis direction, lift and/or lower the uprights for the X-axis.

BTW while I realize that this would add to shipping costs, I'm still wondering if assembling, testing and adjusting the machines at Next Wave wouldn't be the better way to go. Failing that, produce a video and detailed instructions how to test and adjust the machine. I have seen enough "experienced" machine tool fitters measure and adjust in the wrong places, that I wouldn't expect the end user to get it right without detailed instructions.
OTOH it would also be nice to find out what accuracies can be expected out of the box as far as geometry is concerned, that along with the realization that one can't expect the same accuracies as on a machine built from aluminum or steel could help to clear up one or two puzzles. Of course this is strictly my opinion!

PS if your router axis is off by .090"that is a whole lot!
Cheers

HJ
_______
Hans-Joerg Mueller
Coldstream, BC Canada

http://www.rhb-grischun.ca

rungemach
Posts: 460
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Location: Sarasota, Florida

Re: Newbee unable to machine a flat top

Post by rungemach »

Hello John

I second what HJ has said in that it would be very good for the factory to produce a set of assembly and alignment instructions to be sure the adjustments that can be made are made in the correct order.

The machine may be secured down to surfaces that are not exactly flat, and that can also twist the frame out of square.

The sequence I used was:

Rough check the gantry to be 90 degrees from the y axis rails using a square from the y axis rail top to the back of the gantry.(table top off). Adjust to be square by loosening and retightening the bolts that hold the gantry sides to the lower crossmember.

Adjust the height of the table to the router bit at ends of travel x and y. (4 places) Adjust by shimming the table to get these as close to the same as possible. I used a dial indicator in the router position and have about maximum .004" difference at the corners.

Check the squareness of the router to the table. If you use the dial indicator on a swing arm, front to back error (12 and 6 o'clock measurement positions) could be adjusted by the tilt of the gantry forward and back. Error in the 3 to 9 o'clock measurements could be adjusted with the bolts holding the router mount back plate to the z axis bearing blocks ( a small amount).

If this can't get the router bit axis aligned to the table correctly, there may be a problem with the mount assembly,at at least you will know how far off it is and in what direction. Ralph is correct in that you should not see any ridges when you machine your sacrificial top if you are not cutting to hard or fast.

IMHO The first step would be getting the table height even at the corners.

Hope this helps..
Bob

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